Any of the granite areas (Black Hill, You Yangs, Mt Alexander etc) will match the bolts and climbs in the 20 and below grade requirement.

Worthwhile comes down to your personal opinion as to that style of climbing. If you enjoyed the climbing at Black Hill, then these will be good options.

Camels Hump has some worthwhile mostly bolted routes also in the 20 under range. Greasy Grass Gully, Back Wall and Melbourne View Buttress are far from the usual crowds that gather at Camels in Summer and are quite pleasant.